A new study conducted at Stanford university indicates that the multitasking people are less efficient than to those who do single task at a time as brain lacks capabilities to complete both the tasks efficiently. People who feel they have a special skill of doing multiple tasks at time are even worse than those who do one task after the other because the brain was unable organize quickly, move on to the next task quickly to recollect and process the information and filter irrelevant information.
Another observation at university of London, Multitasking (cognitive tasks) actually lowers IQ levels in men to that of an 8 year old and it's required you to do one task at a time especially where you required cognitive abilities to complete the tasks. So, Don't write an email to the subordinate while watching football match.
Anterior cingulate cortex is the important area in your brain which causes empathy, cognitive and emotional control. Brain density around this area is very lower among multitasking people and no signs of physical damage yet. Multi-tasking has negative effects on brain and hence we should be aware of interacting with several devices to organize our brain structure.
Hence, One task at a time....